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After foundation of the Wadden Sea National Park, grazing and artificial drainage was ceased or reduced on large areas of the salt marshes at the Schleswig-Holstein mainland coast (Northern Germany). The effect of grazing cessation versus intensive and moderate grazing on vegetation diversity was studied on small (plant species richness on plots between 0.01 and 100 m2) and large scale (vegetation type richness per hectare) over 18 to 20 years by analysing data from long-term monitoring programs. Plant species richness and vegetation type richness increased strongly over time in all management regimes, because grazing-sensitive species increased first in ungrazed marshes and later dispersed to and established in intensively grazed marshes. Dominance of the tall, late-successional grass Elymus athericus on 7% to 52% of all moderately and ungrazed (primarily high marsh) plots led to a decrease in species richness. After 18 to 20 years, species richness was highest in moderately and intensively grazed high marshes. Differences were significant only on small plots of up to 4 m2. On the large scale, vegetation type richness in the low marsh was higher without grazing, while no differences were found in the high marsh. Our results indicate that grazing effects differ between spatial scales and that different spatial scales have to be considered for monitoring and evaluation of vegetation diversity in salt marshes. To conserve vegetation diversity on all scales, a large-scale mosaic of different management regimes should be maintained.
Im Rahmen des durch die EU geförderten LIFE-Projekts „Lippeaue“ wurden
künstliche Binnendünen angelegt, die Standorte für an Trockenheit und Nährstoffarmut angepasste Pflanzenarten bieten können. Im Jahr 2012 wurde eine Erfolgskontrolle der Vegetationsentwicklung auf den in den Jahren 2008 und 2009 neu geschaffenen Binnendünen durchgeführt.
Die meisten der neu angelegten Dünen in der Lippeaue bei Hamm waren im Jahr 2012 durch Grünlandvegetation auf sandigen und schluffigen Böden gekennzeichnet. Die Gesamtstickstoff-, Humus- und Wassergehalte des Bodens lagen an der oberen Grenze des Bereiches, der für Magerrasenentwicklung günstig ist. Da sich keine Magerrasenbestände in der Nähe befinden, ist eine Etablierung von Magerrasen ohne die gezielte Übertragung von Mahd- oder Rechgut nicht zu erreichen. Die im LIFE-Projekt angelegten Dünen sind daher nur bedingt in einzelnen Fällen für die Magerrasenentwicklung geeignet.
Die ökologische Wertigkeit von Binnendünen ergibt sich aus ihrer Eigenschaft als vegetationsökologisch bedeutsamer Sonderstandort innerhalb des durch Feuchtigkeit geprägten ökosystemaren Wirkungsgefüges der Aue. Wo sich Weidengebüsche auf den Dünen ausbreiten, müssen die Ziele der Auwaldentwicklung durch Sukzession und der Entwicklung von Magerrasen auch durch stärkere Beweidung gegeneinander abgewogen werden.
A floodplain-restoration project along the Danube between Neuburg and Ingolstadt (Germany) aims to bring back water and sediment dynamic to the floodplain. The accompanied long-term monitoring has to document the changes in biodiversity related to this new dynamics. Considerations on and results of the vegetation monitoring concept are documented in this paper. In a habitat rich ecosystem like a floodplain different habitats (alluvial forest, semi-aquatic/aquatic sites) have different demands on the sampling methods.
Therefore, different monitoring designs (preferential, random, systematic, stratified random and transect sampling) are discussed and tested for their use in different habitat types of the floodplain. A stratified random sampling is chosen for the alluvial forest stands, as it guarantees an equal distribution of the monitoring plots along the main driving factors, i.e. influence of water. The parameters distance to barrage, ecological flooding, height above thalweg and distance to the new floodplain river are used for stratifying and the plots are placed randomly into these strata, resulting in 117 permanent plots. Due to small changes at the semi-aquatic/aquatic sites a transect sampling was chosen. Further, a rough stratification (channel bed, river bank adjacent floodplain) was implemented, which was only possible after the start of the restoration project. To capture the small-scale changes due to the restoration measures on the vegetation, 99 additional plots completed the transect sampling. We conclude that hetereogenous study areas need different monitoring approaches, but, later on, a joint analysis must be possible.
15 δ N signals in plant and soil material integrate over a number of biogeochemical processes
related to nitrogen (N) and therefore provide information on net effects of multiple
processes on N dynamics. In general little is known in many grassland restoration projects
on soil–plant N dynamics in relation to the restoration treatments. In particular, 15 δ N signals
may be a useful tool to assess whether abiotic restoration treatments have produced the
desired result. In this study we used the range of abiotic and biotic conditions provided
by a restoration experiment to assess to whether the restoration treatments and/or plant
functional identity and legume neighborhood affected plant 15 δ N signals. The restoration
treatments consisted of hay transfer and topsoil removal, thus representing increasing
restoration effort, from no restoration measures, through biotic manipulation to major
abiotic manipulation. We measured 15 δ N and %N in six different plant species (two nonlegumes and four legumes) across the restoration treatments. We found that restoration
treatments were clearly reflected in 15 δ N of the non-legume species, with very depleted
15 δ N associated with low soil N, and our results suggest this may be linked to uptake of
ammonium (rather than nitrate). The two non-legume species differed considerably in their
15 δ N signals, which may be related to the two species forming different kinds of mycorrhizal
symbioses. Plant 15 δ N signals could clearly separate legumes from non-legumes, but our
results did not allow for an assessment of legume neighborhood effects on non-legume
15 δ N signals. We discuss our results in the light of what the 15 δ N signals may be telling
us about plant–soil N dynamics and their potential value as an indicator for N dynamics in
restoration.
The biennial plant Gentianella bohemica is a subendemic of the Bohemian Massif, where it occurs in seminatural grasslands. It has become rare in recent decades as a result of profound changes in land use. Using amplified fragment length polymorphisms (AFLP) fingerprint data, we investigated the genetic structure within and among populations of G. bohemica in Bavaria, the Czech Republic, and the Austrian border region. The aim of our study was (1) to analyze the genetic structure among populations and to discuss these findings in the context of present and historical patterns of connectivity and isolation of populations, (2) to analyze genetic structure among consecutive generations (cohorts of two consecutive years), and (3) to investigate relationships between intrapopulational diversity and effective population size (Ne) as well as plant traits. (1) The German populations were strongly isolated from each other (pairwise FST= 0.29–0.60) and from all other populations (FST= 0.24–0.49). We found a pattern of near panmixis among the latter (FST= 0.15–0.35) with geographical distance explaining only 8% of the genetic variance. These results were congruent with a principal coordinate analysis (PCoA) and analysis using STRUCTURE to identify genetically coherent groups. These findings are in line with the strong physical barrier and historical constraints, resulting in separation of the German populations from the others. (2) We found pronounced genetic differences between consecutive cohorts of the German populations (pairwise FST= 0.23 and 0.31), which can be explained by local population history (land use, disturbance). (3) Genetic diversity within populations (Shannon index, HSh) was significantly correlated with Ne (RS= 0.733) and reflected a loss of diversity due to several demographic bottlenecks. Overall, we found that the genetic structure in G. bohemica is strongly influenced by historical periods of high connectivity and isolation as well as by marked demographic fluctuations in declining populations.
During recent decades, many studies have shown that the successful restoration of species-rich grasslands is often seed-limited because of depleted seed banks and limited seed dispersal in modern fragmented landscapes. In Europe, commercial seed mixtures, which are widely used for restoration measures, mostly consist of species and varieties of non-local provenance. The regional biodiversity of a given landscape, however, can be preserved only when seeds or plants of local provenance are used in restoration projects. Furthermore, the transfer of suitable target species of local provenance can strongly enhance restoration success.
We review and evaluate the success of currently used near-natural methods for the introduction of target plant species (e.g. seeding of site-specific seed mixtures, transfer of fresh seed-containing hay, vacuum harvesting, transfer of turves or seed-containing soil) on restoration sites, ranging from dry and mesic meadows to floodplain grasslands and fens. Own data combined with literature findings show species establishment rates during the initial phase as well as the persistence of target species during long-term vegetation development on restoration sites.
In conclusion, our review indicates that seed limitation can be overcome successfully by most of the reviewed measures for species introduction. The establishment of species-rich grasslands is most successful when seeds, seed-containing plant material or soil are spread on bare soil of ex-arable fields after tilling or topsoil removal, or on raw soils, e.g. in mined areas. In species-poor grasslands without soil disturbance and on older ex-arable fields with dense weed vegetation, final transfer rates were the lowest. For future restoration projects, suitable measures have to be chosen carefully from case to case as they differ considerably in costs and logistic effort. Long-term prospects for restored grassland are especially good when management can be incorporated in agricultural systems.
The aim of this study is to assess the development of plant species diversity and species composition
over a seven-year period in two calcareous grasslands abandoned for nearly 20 years and to find out
which factors influence vegetation dynamics. In the Abava River valley, Latvia, different calcareous
grasslands were studied, one on the south-west facing slope and another on the north-east facing slope.
Vegetation analyses on permanent plots showed that dry calcareous grasslands can be resistant to deterioration for a long period of time – succession was slower than reported in many cases for Central and
Western Europe. None of the studied communities showed a decrease neither in total species number
recorded per community nor in average species richness per plot. Vascular plant species richness even
increased by 3–4 species per 1-m² plot in the grassland on the south-west facing slope. An unexpected
result of the research was that Calamagrostis epigeios did not expand in this grassland. This fact can be
explained by the influence of disturbances (drought, tree cutting) and local differences in soil parameters
and topography. In parts of the north-east exposed grassland, with deeper soils and better water availability, species diversity (Shannon index) decreased significantly in areas overgrown by Aegopodium
podagraria.